At 12:15 last night I filled the stove. When I awoke at 7:30 this morning, it was as cold as a well diggers shovel. Had to empty it and start over. 2 full pans of ash and little bits of unburned coal as well. See you soon!

JC

Last edited by Wood'nCoal on Sun Nov 18, 2007 12:10 am, edited 1 time in total.

LsFarm wrote:UPDATE Both motors are rated 1/2 horse, but the new, higher effeciency one just doesn't have the starting torque of the old one. The lights would dim and the fan/auger would take several seconds to accelerate up to speed. With the old original motor, the fan/auger is up to speed in 1-2 seconds without any dimming of the lights or hesitation. The old motor is noisy, I'm hoping the bearings will last till Monday when I'm buying a new motor and replacement bearings to refurb the old motor for a spare. So for now I'm back in business, I'll see how the AA does over the next few days, and I'll install a fresh new 'Farm Duty' motor on Monday. Maybe I'll find time to build my bigger coal bin tomorrow. Greg L

Greg: I doubt that the problem with the new motor was that it is "high efficiency"--rather that it is not designed for high starting torque. You definitely need a capacitor start motor and should specifically spec high starting torque. It will not be cheap. I checked the replacement cost for the fan motor (only the grate shaker is a separate motor on the AHS) that came on my new AHS 130--approximately $200.

Hi Bob, the original motor is a Dayton 6k122, currently at Grainger for about $200. A better motor, with higher starting torque [farm duty] is a 6K592, available from Grainger for $126.00.

The new motor I had was a donation to the resurection project, and I really wanted to make it work. But it just wasn't up to the job. What confuses me is that horsepower is torque x rpm. So if both motors are 1725 rpm, then the torque should be the same. This motor is a capacitor start motor, but just can't handle the starting loads the AA boiler puts on it.. It is higher effeciency, it is rated at 8.0 amps compared to 9.4 amps for the other motors. So IF it is really 1/2 horse it is doing it with less torque and lower amperage draw...??? Sounds like marketing rated the motor instead of engineering

The original 6K122 motor is doing the job, and the bearings don't seem to be getting any louder so hopefully it will survive untill Monday.

I'm no electrician, but the starting torque may be related to the number of wraps each armature segment gets of its wire. I would think the more wraps per segment, the stronger the magnetic field and the higher the starting torque. Yes, no, maybe? Don't electric motors make peak torque at startup or is that just steam engines?

LsFarm wrote:What confuses me is that horsepower is torque x rpm. So if both motors are 1725 rpm, then the torque should be the same. Greg L

I think that the horsepower rating is a "running" rating. However it is not directly related to staring power. Another critical factor in motors is the service factor (SF). A 1/2 HP motor might have a service factor of 1.15 meaning that it can routinely deliver 1.15 times 1/2 HP. Another 1/2 HP motor might have a service factor of 1.9--much more available power.

Unless you understand all the rating factors on electrical motors I would suggest you consult with a knowledgeable supplier to ensure you are getting what you need. The fact that the original motor cost $200 and you are looking at a replacement at $126 suggests that there is a big difference between the motors. The difference might be important and it might not. I don't know enough to tell you one way or the other.

Somewhere around here I have a booklet that explains all the differences in types of electric motors, but I can't seem to find it. My knowledge is somewhat limited, but I do know that different motors which have the same HP rating have different start-up torque. You need a motor with a higher start-up torque rating and the same RPM rating. HP can be the same, or slightly higher.

A Split-Phase AC motor uses a separate set of windings to provide higher start-up torque to get the equipment turning. Then when the RPM's hit running speed, the motor switches to the run windings. This a because single phase motors cannot provide enough torque to start the motor turning. 3 phase motors do not require start-up windings because they can generate enough torque with out them.

A capacitor start motor uses a capacitor to create a second phase to help start the motor. A capacitor run motor uses a cap to create a second phase when ever a motor is running.

You need a Split Phase motor on the AA, it can provide the start-up torque you need. A cap start motor is usually used in applications with little or no start-up load (AC fan motors, etc.) where the load builds up as the motor speeds up. Split Phase is for applications where the load is present at start-up.

1) No start-up load, light running load-Induction motor.

2) Little or no start-up load, medium running load-Capacitor start or run motor.

What I've learned: There are NO GRAPHS of start torque, hp at rpm, running torque etc. Even finding what the h#LL 'farm duty meant was a struggle. The motor industry apparently lives on 'old knowledge' and word-of-mouth. Just as an asside:, the water pump industry has graphs galore of flow vs. head pressure, amp use etc. All available online.

The two 6K Dayton motors are 7" diameter, cap start motors, The 'specialty duty' motor is only 5" diameter, cap start. The capacitor is much bigger, 450-550uf vs 330-380uf on the larger motors. The larger diameter motor and armature provide a LOT more torque, at the expense of a higher amp load under continous duty.

So it appears that the smaller specialty motor is a low torque, large capacitor-start motor that is not capable of pulling the start torque needed to get the fan and auger turning on the AA boiler. However once running it would have used less electricity. But since the AA boiler starts and stops several times an hour, I need a strong starting motor.

This morning the motor is much quieter, the bearings seem to have 'run in' a bit. I removed the belts and gave it a hand spin and a test run, the motor is sounding much better than last night.

Another observation Last night was the first full night of uninterupted use of the boiler. And I found another 'issue'.

The previous owner / operator must have compensated for the worn out grate linkage by turning the ash sensing temp to make the grate run almost continously. Since I was not able to read the markings on the temp sensor I left it alone. So last night I used a lot of coal, and a lot of half burnt coal was in the ash pan. $$%$$^& !!!

So I adjusted the temp sensor way down to the point that very little heat was required to have it stop the grate from shaking. Since I was able to maintain a fire for 5 days without any fan draft or grate shaking last week, I believe that I have the temp sensor set at a good starting point for 'fine-tuning' the setting.

The AA boiler manual is pretty specific about not using the black plastic knob to turn the temp adjustment, because it will slip on the shaft and ruin the calibration. Well this apparently happened to this temp sensor, so the pointer is just an indication, pointing at an irrelevant number on the scale.

LsFarm wrote:This morning the motor is much quieter, the bearings seem to have 'run in' a bit. I removed the belts and gave it a hand spin and a test run, the motor is sounding much better than last night.

Greg, what I listed below is what I have on my 260 but I can say that I'm having the issues as you are with the slow starting... what I would like to know is that Dayton # you talk about the motor AA used if your not sure thats ok I might be on the phone monday to find out and get the right one for mine....also atached are two .mov clips of the "SPIN UP" of my AA for your comparison.

From the Rear

http://www.engtechs.com/temp/coal/102_3972.movThis link is broken, either the page no longer exists or there is some other issue like a typo.

From the Front

http://www.engtechs.com/temp/coal/102_3972.movThis link is broken, either the page no longer exists or there is some other issue like a typo.